ACCUMULATED OTHER COMPREHENSIVE INCOME, NET (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020
AOCI Rollforward
Beginning balance	$ 3,310.1	$ 3,355.6	$ 3,285.4	$ 3,241.0	$ 3,355.6
Other comprehensive income (loss)	(2.7)	(37.5)	(18.1)	14.7
Ending balance	3,286.3	3,310.1	3,327.0	3,285.4	3,286.3
Accumulated Other Comprehensive Income, net
AOCI Rollforward
Beginning balance	0.1	37.6	26.2	11.5	37.6
Other comprehensive income (loss)	(2.7)	(37.5)	(18.1)	14.7	(40.2)
Ending balance	(2.6)	0.1	$ 8.1	$ 26.2	(2.6)
Foreign Currency Translation
AOCI Rollforward
Beginning balance		38.2			38.2
Other comprehensive income (loss)					(41.0)
Ending balance	(2.8)				(2.8)
Unrealized Investment Gain/Loss
AOCI Rollforward
Beginning balance		0.2			0.2
Other comprehensive income (loss)					(0.3)
Ending balance	(0.1)				(0.1)
Post-Retirement Benefits
AOCI Rollforward
Beginning balance		$ (0.8)			(0.8)
Other comprehensive income (loss)					1.1
Ending balance	$ 0.3				$ 0.3